Keywords:
island barrier dunes
artificial foredune
marram grass
stabilisation
succession
Contact: W.H. van der Putten. Netherlands Institute
of Ecology. P.O. Box 40. NL-6666 ZG Heteren. The Netherlands.
E-mail putten@cto.nioo.knaw.nl.
Location: The Netherlands, Province of Zuid-Holland,
Oostvoorne - Rockanje
The foredunes of Voorne
The Voorne dunes are situated south of the Maasvlakte harbour
area in the southwestern part of the Netherlands. The region as
a whole is an estuarine area, the dunes border not only the North
Sea but also parts of the estuaries. All these dunes belong to
the Younger Dunes, developed since 1100 AD. The dune sand is quartz
sand of riverine origin (rivers Rhine and Meuse) and somewhat
finer than that along the northern coasts of the Netherlands.
The dunes in Voorne are generally low, approximately 10-15 m.
The study area faces Northwest in the northern area and Southwest
in the southern part. The construction of the offshore harbour
area ‘Maasvlakte’ has reduced the influence of sand deposition
and salt spray in the northern part.
Management
The 9.4 km long foredune ridge was raised and widened in three
phases between 1984 and 1988. Each phase was started in the winter
with the offshore dredging of Pleistocene sand and storage at
a depot on the beach temporary stabilised with straw between March
and September. In the subsequent winter, the sand depots were
reshaped into a foredune landscape by bulldozers, cranes and scrapers
and planted with Ammophila arenaria (marram grass) using
seven different treatments: (1) seeds with compost, (2) seeds
with straw, (3) seeds with cereal rye, (4) culms with reed, (5)
culms and rhizomes with reed, (6) rhizomes with reed and (7) rhizomes
with straw. All plant material was collected from the local foredune
area. Rabbit browsing was prevented by fencing. The total experimental
area covered more than 100 ha and the vegetation development was
studied for 6 years.
Results
Vegetation development was influenced by the method of establishing
marram grass. The main con-trast between the different planting
methods was that using rhizome material resulted in a higher per-centage
cover of clonal perennials, whereas using seeds and culms favoured
a vegetation dominated by (mostly) non-clonal dicots. In the first
year, stands established by culms produced less biomass and soil
cover, but the reverse appeared in the second year. Culms gave
the most homogenous soil cover and seeds the least. Comparing
ecological groups of plants showed that all planting methods delivered
equal numbers of plant species characteristic of coastal foredunes.
At exposed sites succession lead to an Ammophila-dominated
vegetation type, landward the development of vegetation proceeded.
Initially, the rates of succession were highest in the stands
obtained from rhizomes, but after 3-5 years this apparent difference
disappeared. During the first four years, the percentage cover
by rhizomatous foredune plants developed faster than that of annuals,
bi-annuals and perennials. After 6 years, the latter contributed
almost as much to the percentage cover as the clonal species.
For the management of foredune sites where sand deposition is
insufficient to guarantee ample vigour of Ammophila for
erosion control, methods based on the use of rhizomes are advised.
This favours the introduction of a perennial sand-stabilizing
vegetation.
Experimental area with the situation of the stands of A.
arenaria
as established according to the different techniques
References
- van der Laan, D., O.F.R. van Tongeren, W.H. Putten &
G. Veenbaas (1997): Vegetation development in coastal
foredunes in relation to methods of establishing marram grass
(Ammophila arenaria). Journal of Coastal Conservation
3: 179-190. EUCC. Opulus Press Uppsala. Sweden. (KJc97b).
- van der Meulen, F. & E. van der Maarel (1993):
Dry coastal ecosystems of the central and southwestern Netherlands.
In: van der Maarel (ed.). Ecosystems of the world 2A: 271-306.
Elsevier. Amsterdam-London-New York-Tokyo. (BN93).
